qfocusframe.cpp

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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#include "qfocusframe.h"
#include "qstyle.h"
#include "qbitmap.h"
#include "qstylepainter.h"
#include "qstyleoption.h"
#include "qdebug.h"
#include <private/qwidget_p.h>
 
QT_BEGIN_NAMESPACE
 
class QFocusFramePrivate : public QWidgetPrivate
{
    Q_DECLARE_PUBLIC(QFocusFrame)
    QWidget *widget;
    QWidget *frameParent;
    bool showFrameAboveWidget;
public:
    QFocusFramePrivate() {
        widget = nullptr;
        frameParent = nullptr;
        sendChildEvents = false;
        showFrameAboveWidget = false;
    }
    void updateSize();
    void update();
};
 
void QFocusFramePrivate::update()
{
    Q_Q(QFocusFrame);
    q->setParent(frameParent);
    updateSize();
    if (q->parentWidget()->rect().intersects(q->geometry())) {
        if (showFrameAboveWidget)
            q->raise();
        else
            q->stackUnder(widget);
        q->show();
    } else {
        q->hide();
    }
}
 
void QFocusFramePrivate::updateSize()
{
    Q_Q(QFocusFrame);
    if (!widget)
        return;
 
    QStyleOption opt;
    q->initStyleOption(&opt);
    int vmargin = q->style()->pixelMetric(QStyle::PM_FocusFrameVMargin, &opt),
        hmargin = q->style()->pixelMetric(QStyle::PM_FocusFrameHMargin, &opt);
    QPoint pos(widget->x(), widget->y());
    if (q->parentWidget() != widget->parentWidget())
        pos = widget->parentWidget()->mapTo(q->parentWidget(), pos);
    QRect geom(pos.x()-hmargin, pos.y()-vmargin,
               widget->width()+(hmargin*2), widget->height()+(vmargin*2));
    if (q->geometry() == geom)
        return;
 
    q->setGeometry(geom);
 
    opt.rect = q->rect();
    QStyleHintReturnMask mask;
    if (q->style()->styleHint(QStyle::SH_FocusFrame_Mask, &opt, q, &mask))
        q->setMask(mask.region);
}
 
void QFocusFrame::initStyleOption(QStyleOption *option) const
{
    if (!option)
        return;
 
    option->initFrom(this);
}
 
QFocusFrame::QFocusFrame(QWidget *parent)
    : QWidget(*new QFocusFramePrivate, parent, { })
{
    setAttribute(Qt::WA_TransparentForMouseEvents);
    setFocusPolicy(Qt::NoFocus);
    setAttribute(Qt::WA_NoChildEventsForParent, true);
    setAttribute(Qt::WA_AcceptDrops, style()->styleHint(QStyle::SH_FocusFrame_AboveWidget, nullptr, this));
}
 
QFocusFrame::~QFocusFrame()
{
}
 
void
QFocusFrame::setWidget(QWidget *widget)
{
    Q_D(QFocusFrame);
 
    if (style()->styleHint(QStyle::SH_FocusFrame_AboveWidget, nullptr, this))
        d->showFrameAboveWidget = true;
    else
        d->showFrameAboveWidget = false;
 
    if (widget == d->widget)
        return;
    if (d->widget) {
        // Remove event filters from the widget hierarchy.
        QWidget *p = d->widget;
        do {
            p->removeEventFilter(this);
            if (!d->showFrameAboveWidget || p == d->frameParent)
                break;
            p = p->parentWidget();
        }while (p);
    }
    if (widget && !widget->isWindow() && widget->parentWidget()->windowType() != Qt::SubWindow) {
        d->widget = widget;
        d->widget->installEventFilter(this);
        QWidget *p = widget->parentWidget();
        QWidget *prev = nullptr;
        if (d->showFrameAboveWidget) {
            // Find the right parent for the focus frame.
            while (p) {
                // Traverse the hirerarchy of the 'widget' for setting event filter.
                // During this if come across toolbar or a top level, use that
                // as the parent for the focus frame. If we find a scroll area
                // use its viewport as the parent.
                bool isScrollArea = false;
                if (p->isWindow() || p->inherits("QToolBar") || (isScrollArea = p->inherits("QAbstractScrollArea"))) {
                    d->frameParent = p;
                    // The previous one in the hierarchy will be the viewport.
                    if (prev && isScrollArea)
                        d->frameParent = prev;
                    break;
                } else {
                    p->installEventFilter(this);
                    prev = p;
                    p = p->parentWidget();
                }
            }
        } else {
            d->frameParent = p;
        }
        d->update();
    } else {
        d->widget = nullptr;
        hide();
    }
}
 
QWidget *
QFocusFrame::widget() const
{
    Q_D(const QFocusFrame);
    return d->widget;
}
 
 
void
QFocusFrame::paintEvent(QPaintEvent *)
{
    Q_D(QFocusFrame);
 
    if (!d->widget)
        return;
 
    QStylePainter p(this);
    QStyleOption option;
    initStyleOption(&option);
    const int vmargin = style()->pixelMetric(QStyle::PM_FocusFrameVMargin, &option);
    const int hmargin = style()->pixelMetric(QStyle::PM_FocusFrameHMargin, &option);
    QWidgetPrivate *wd = qt_widget_private(d->widget);
    QRect rect = wd->clipRect().adjusted(0, 0, hmargin*2, vmargin*2);
    p.setClipRect(rect);
    p.drawControl(QStyle::CE_FocusFrame, option);
}
 
 
bool
QFocusFrame::eventFilter(QObject *o, QEvent *e)
{
    Q_D(QFocusFrame);
    if (o == d->widget) {
        switch(e->type()) {
        case QEvent::Move:
        case QEvent::Resize:
            d->updateSize();
            break;
        case QEvent::Hide:
        case QEvent::StyleChange:
            hide();
            break;
        case QEvent::ParentChange:
            if (d->showFrameAboveWidget) {
                QWidget *w = d->widget;
                setWidget(nullptr);
                setWidget(w);
            } else {
                d->update();
            }
            break;
        case QEvent::Show:
            d->update();
            show();
            break;
        case QEvent::PaletteChange:
            setPalette(d->widget->palette());
            break;
        case QEvent::ZOrderChange:
            if (style()->styleHint(QStyle::SH_FocusFrame_AboveWidget, nullptr, this))
                raise();
            else
                stackUnder(d->widget);
            break;
        case QEvent::Destroy:
            setWidget(nullptr);
            break;
        default:
            break;
        }
    } else if (d->showFrameAboveWidget) {
        // Handle changes in the parent widgets we are monitoring.
        switch(e->type()) {
        case QEvent::Move:
        case QEvent::Resize:
            d->updateSize();
            break;
        case QEvent::ZOrderChange:
            raise();
            break;
        default:
            break;
        }
    }
    return false;
}
 
bool QFocusFrame::event(QEvent *e)
{
    Q_D(QFocusFrame);
 
    switch (e->type()) {
    case QEvent::Move:
    case QEvent::Resize:
        if (d->widget) {
            // When we're tracking a widget, we don't allow anyone to move the focus frame around.
            // We do our best with event filters to make it stay on top of the widget, so trying to
            // move the frame somewhere else will be flaky at best. This can e.g happen for general
            // purpose code, like QAbstractScrollView, that bulk-moves all children a certain distance.
            // So we need to call updateSize() when that happens to ensure that the focus frame stays
            // on top of the widget.
            d->updateSize();
        }
        break;
    default:
        return QWidget::event(e);
    }
    return true;
}
 
QT_END_NAMESPACE
 
#include "moc_qfocusframe.cpp"